In this paper, a new sorting method, following a decision aiding constructive approach, is proposed. This method is called Electre Tri-C. As a sorting method, a set of categories must be defined to represent the way in which the actions that are going to be assigned to each of them should further be processed. This method is appropriate to deal with decision aiding contexts where the categories are completely ordered and each of them is defined through a single characteristic reference action. The set of characteristic actions should be co-constructed through an interactive process between the analyst and the decision maker. Electre Tri-C has been conceived to verify a set of natural structural requirements (conformity, homogeneity, monotonicity, and stability), which can be viewed as its fundamental properties. This method is composed of two joint rules, called descending rule and ascending rule, which must be used conjointly (and not separately). Each one of these rules selects only one category or a range of possible categories for a possible assignment of an action. This assignment depends on the comparison of such an action to the characteristic actions according to a chosen credibility level. Numerical examples are also presented in order to illustrate the main theoretical results provided by the method.
